Chuck for Reciprocating Surgical Instrument

ABSTRACT

Devices are described relating to the retaining of surgical tools within the chuck of a reciprocating surgical instrument, such as a reciprocating saw. A securing chuck is disclosed for securing a surgical tool to a reciprocating surgical instrument that comprises a shaft and a securing member. The shaft defines an axis and has a cylindrical bore extending along the axis. The bore is shaped to receive a substantially rounded tool shank. A pair of transverse slots extends into the shaft along a plane passing through the axis for receiving a substantially flattened tool shank. The transverse slots intersect with the cylindrical bore. The securing member is carried by the shaft and is radially movable relative to the bore both inwardly and outwardly to secure the surgical tool in the chuck.

FIELD OF THE INVENTION

The present invention relates generally to reciprocating surgicalinstruments used for cutting and modifying bone or other tough tissues.In particular, the present invention relates to a chuck or collet foruse with said instruments, and especially for securing various bladesand other tools to said instruments.

BACKGROUND

Doctors and other medical professionals often use powered surgicalinstruments for dissecting bones, tissues and other purposes.Reciprocating saw-type cutting instruments may be used for surgicaloperations to cut through bone, cartilage, or other strong tissue.Depending on the manufacture or purpose, saw blades, bone burs, rasps,chisels, and other tools are often designed with varying tool profiles,such as flat or round shank profiles. It would be an improvement to havea reciprocating motion surgical instrument with a chuck that can readilyaccept blades, and other tools, having flat, round, or other shankprofiles.

SUMMARY

The present invention provides improved methods and devices for securinga surgical tool, such as a cutting blade within a reciprocating surgicalinstrument, such as a reciprocating saw. Cutting blades and othersurgical tools are described that are provided with flat, round, orother shank profiles.

According to one exemplary embodiment, a chuck is disclosed for securinga surgical tool having a shank with a securing aperture within areciprocating motion surgical instrument. The chuck comprises a shaftand a securing member. The shaft defines an axis and has a receptaclefor receiving the shank of the tool. The securing member is carried bythe shaft and is selectively moveable between a first position whereinthe member is substantially withdrawn from the receptacle to permit theinsertion and removal of the surgical tool, and a second positionwherein the member is substantially located within the receptacle andthrough the securing aperture to secure the surgical tool within thereceptacle.

In another aspect, a securing chuck is disclosed for securing a surgicaltool to a reciprocating surgical instrument that comprises a shaft and asecuring member. The shaft defines an axis and has a cylindrical boreextending along the axis. The bore is shaped to receive a substantiallyrounded tool shank. A pair of transverse slots extends into the shaftalong a plane passing through the axis for receiving a substantiallyflattened tool shank. The transverse slots intersect with thecylindrical bore. The securing member is carried by the shaft and isradially movable relative to the bore both inwardly and outwardly tosecure the surgical tool in the chuck.

In some embodiments, a reciprocating surgical instrument comprises amotor, a transmission, a surgical tool chuck, and a surgical tool. Themotor has a rotatable spindle and a transmission is mounted to thespindle for converting rotating movement of the spindle to reciprocatingmovement. The surgical tool chuck is coupled to the transmission andcomprises a receiving shaft, a locking member, and a camming sleeve. Thereceiving shaft defines an longitudinal axis and has a tool receptacleand a radially extending proximal opening. The locking member isslidingly coupled to the receiving shaft and has a protrusion extendingtherefrom. The camming sleeve is rotatingly retained on the shaft andhas an internally cammed surface. The surgical tool has a distal end anda proximal end, the proximal end configured to be received into the toolreceptacle. The surgical tool has an aperture disposed to correspondwith the radially extending proximal opening of the receiving shaft whenthe surgical tool is disposed in the attachment receptacle. The lockingmember is selectively moveable between a first position and a secondposition. In the first position the protrusion is withdrawn from theproximal opening of the receiving shaft to allow insertion and removalof the surgical tool. In the second position the protrusion issubstantially received within the proximal opening of the receivingshaft and the aperture in the surgical tool to secure the surgical toolwithin the chuck. The cammed surface is configured to urge theprotrusion into the second position.

It should be understood that the present summary and the followingdetailed description, while discussing some exemplary embodiments of theinvention, are intended for purposes of illustration only and are notintended to limit the scope of the invention beyond that described inthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1A is a cutaway, cross-sectional view of an exemplary reciprocatingmotion surgical instrument constructed in accordance with the presentinvention.

FIG. 1B is another cutaway, cross-sectional view of the exemplaryreciprocating motion surgical instrument of FIG. 1A.

FIG. 2 is an enlarged cutaway, cross-sectional view of an exemplarychuck for use with the surgical instrument of FIGS. 1A and 1B.

FIG. 3 is an exploded view of the chuck depicted in FIG. 2.

FIG. 4 is a another enlarged cutaway, cross-sectional view of theexemplary chuck in FIG. 2.

FIG. 5 is a an end view of a portion of the chuck of FIG. 2.

FIG. 6A is a top view of an exemplary blade for use with the chuck ofFIG. 2.

FIG. 6B is a top view of another exemplary blade for use with the chuckof FIG. 2.

FIG. 7A is a cutaway, cross-sectional view of the blade of FIG. 6Ainstalled in the chuck of FIG. 2.

FIG. 7B is another cutaway, cross-sectional view of the blade of FIG. 6Ainstalled in the chuck of FIG. 2.

FIG. 8 depicts an exemplary cutting blade having a rounded shankinstalled in the chuck of FIG. 2.

FIG. 9A depicts an exemplary rasp tool having a rounded shank installedin the chuck of FIG. 2.

FIG. 9B depicts an exemplary rasp tool having an angled shank.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of theinvention, references will now be made to the embodiments, or examples,illustrated in the drawings and specific languages will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the invention is thereby intended. Any alterations andfurther modifications in the described embodiments, and any furtherapplications of the principles of the invention as described herein arecontemplated as would normally occur to one skilled in the art to whichthe invention relates. Further, it will be understood that the presentdisclosure is not limited to any particular surgical application but hasutility for various applications in which it is desired, including butnot limited to:

1. Arthroscopy—Orthopedic

2. Endoscopic—Gastroenterology, Urology, Soft Tissue

3. Neurosurgery—Cranial, Spine, and Otology

4. Small Bone—Orthopedic, Oral-Maxiofacial, Ortho-Spine, and Otology

5. Cardio Thoracic—Small Bone Sub-Segment

6. Large Bone—Total Joint and Trauma

7. Dental and other applications

Certain details of the construction of the instrument will be understoodby those of skill in the art and, therefore, are not described in detailhere.

Referring generally to FIGS. 1A and 1B, two cutaway, cross-sectionalviews of an exemplary reciprocating motion surgical instrument 10 areshown. Instrument 10 has a distal working portion 12 adapted to hold acutting blade, or other surgical tool or attachment, and a proximaldriver portion 14 containing a motor 15 for operating working portion12. Motor 15 has a splined spindle 17 on its forward, or distal, endthat is rotated by motor 15.

Driver portion 14 is partially enclosed by a tapered nose piece 16 thatdefines a longitudinal bore 18 and has exterior threads 20 at its rear,or proximal, end and interior threads 22 at its forward, or distal, end.Interior threads 22 secure a cap 24 within the length of bore 18 of thenose piece, cap 24 providing a chamber 26 therein. Exterior threads 20of nose piece 16 are secured to mating interior threads 28 on motorhousing 30.

As can be seen from FIG. 1A, motor housing 30 provides a rearwardreceptacle 32 with an interiorly threaded portion 34. A couplingassembly 36 resides within receptacle 32 and has exterior threads 38which mate with threads 34 of motor housing 30 to secure the twocomponents together. Coupling assembly 36 has a central fluid passage 40that extends longitudinally through assembly 36. It is noted thatcoupling assembly 36 is interconnected with a fluid pressure source (notshown), typically by a coaxial hose or conduit, that providespressurized fluid (e.g., air) into the fluid passage 40. Radiallyinterior and radially exterior slip-on fittings 42 and 44, respectively,form a seal with the coaxial hose, in a manner known in the art.

Pressurized fluid is directed from central passage 40 through an angledconduit 46 to drive motor 15. Exhaust fluid is communicated from motor15 back to the coaxial hose through radially disposed fluid exhaustpassages 47 in coupling assembly 36.

Coupling assembly 36 presents a radially expanded outer portion 48 thatis shaped to provide either a knurled surface or wrench flats so thatcoupling assembly 36 can be more easily rotated when being affixed orremoved from receptacle 32 of motor housing 30.

Referring to FIG. 1B, a motor sleeve 50 surrounds motor 15 and iscontained within motor housing 30. Motor sleeve 50 is positionedforward, or distally, of coupling assembly 36 and abuts a gear housing52 that is generally cylindrical in shape. Gear housing 52 has a centrallongitudinal bore 54 of reduced diameter and an enlarged diameterlongitudinal bore 56 at its rear, or proximal, end. The rear portion ofenlarged diameter bore 56 is interiorly threaded at 58.

Enlarged diameter bore 56 houses a gear coupling 60 that defines asplined longitudinal passage 62 therein that is adapted to surround andengage the splines of motor spindle 17 in a complimentary fashion. Apair of annular bearings 64 are disposed between gear coupling 60 andbore 56 to aid in rotation of gear coupling 60.

The distal portion of passage 62 is threaded, as shown at 66. A piniongear 68 is secured within threaded portion 66 and provides a set ofangled rotary teeth 70 at its forward end. It will be seen that whenmotor 15 is activated, the set of teeth 70 is rotated by the motor 15.

As shown in FIG. 1A, a pair of lateral bores 72 are cut into gearhousing 52 in diametrically opposite locations, and each of the bores 72houses an annular bearing 74. An eccentric crank 76 is maintained withinlongitudinal bore 54 and provides bearing pins 78 that extend outwardthrough bearings 74 so that pins 78 can rotate within bearings 74 abouttheir own pin axis 80. Eccentric crank 76 has a central spanning portion82 that is offset from pin axis 80 so that it revolves about pin axis 80when bearing pins 78 are rotated inside their bearings 74. Eccentriccrank 76 also provides a pinion gear portion 84 having angled teeth thatintermesh with teeth 70 of pinion gear 68. When pinion gear 68 isrotated by motor 15, teeth 70 of gear 68 engage the teeth of pinion gearportion 84 so that eccentric crank 76 is rotated by its bearing pins 78within bearings 74. As crank 76 is rotated in this manner, spanningportion 82 is rotated about pin axis 80.

As best shown in FIG. 1B, a connecting rod 86 contained within bore 26interconnects spanning portion 82 of eccentric crank 76 to areciprocating shaft 88. Connecting rod 86 has a proximal opening 90 anda distal opening 92. Both openings 90 and 92 contain annular bearings94. Spanning portion 82 passes through proximal opening 90 and bearing94. Distal opening 92 and bearing 94 surround a pin 96 withinreciprocating shaft 88. It is noted that the reciprocating shaft 88 isdisposed substantially within chamber 26 of cap 24 and within bore 18 ofnose piece 16. It will be understood, then, that the componentsdescribed herein provide a transmission that converts rotating movementof motor spindle 17 into reciprocating movement for shaft 88 and relatedcomponents. A number of bearings and sleeves, which will not bedescribed in detail here, ensure that reciprocating shaft 88 is capableof reciprocating movement within cap 24 and nose piece 16.

The distal end of reciprocating shaft 88 extends outward beyond thedistal end of cap 24, and contains a blind bore 98 that is formedtherein. Blind bore 98 has an inner threaded portion 100 along itslength whereby reciprocating shaft 88 can be connected to workingportion 12 of instrument 10.

While instrument 10 has been described as having a pneumatic motor, itis contemplated that working portion 12 and the necessary transmissioncomponents may be similarly driven by an electric motor and handpiece.One exemplary electric handpiece is the Midas Rex® Legend EHS Stylus™owned by Medtronic Xomed, Inc. Thus, an electric motor may provide arotational force that the transmission converts into reciprocatingmovement for reciprocating shaft 88.

Working portion 12 of instrument 10 is more easily understood withfurther reference to FIGS. 2-6, wherein a chuck and other components ofworking portion 12 are shown in greater detail. FIG. 2 is an enlargedcutaway, cross-sectional view of an exemplary collet, or securing chuck102 for use with instrument 10. Securing chuck 102, according oneexemplary embodiment, comprises a securing shaft 104 which carriesexternal threads 106 near its proximal end. Threads 106 are shaped andsized to interconnect with the threads 100 of blind bore 98 inreciprocating shaft 88 (shown in FIG. 1B). In other embodiments,securing shaft 104 and reciprocating shaft 88 are integral, or amonolith. In yet other embodiments, the transmission may be integralwith chuck 102.

Referring now to FIGS. 3 and 4, FIG. 3 is an exploded view of the chuck102 and FIG. 4 is across-sectional view of chuck 102. Shaft 104 has alateral hole 108 laterally extending through its diameter. The distalend of securing shaft 104 contains a substantially-rounded receivingbore 110 that is centrally located within shaft 104 and aligned along alongitudinal axis L. A pair of slots 112 extend radially outward frombore 110 and are located diametrically across from one another.

Still referring to FIGS. 2 and 3, shaft 104 also has an exteriorindentation 114 along one side (best shown in FIG. 3). A pair of springretaining slots 116 are formed within the indentation 114 to providereceiving elements in shaft 104 within which springs 118 may rest. Akey-hole 120 is cut through indentation 114.

As best shown in FIG. 3, a retaining sleeve 122 surrounds shaft 104 andis substantially cylindrical in shape. Sleeve 122 includes a centrallongitudinal bore 124 within which shaft 104 resides. A pair of lateralholes 126 and a slot 127 are cut through sleeve 122. Sleeve 122 mayinclude other features, such as a sealing member retainer groove 125.

A rotatable camming sleeve 128 surrounds shaft 104 and retaining sleeve122 and provides outer ridged or textured gripping surface 130. FIG. 5is an end view of camming sleeve 128. With reference to FIGS. 3 and 5,camming sleeve 128 is hollow and provides a pair of surfaces that retaincamming sleeve 128 against retaining sleeve 122, and activate a shanksecuring member in a manner that will be described.

An interior camming surface portion 132 is presented upon the interiordistal portion of camming sleeve 128. Camming surface portion 132 iseccentrically graduated as shown in FIG. 3, and more especially in FIG.5, so that one side 132 a of camming surface portion 132 is radiallycloser to axis L than an opposing side 132 b of camming surface portion132. As shown particularly in FIGS. 2 and 5, camming sleeve 128 alsoprovides an interior radial contact surface portion 134 that is equallyspaced about its circumference from axis L and adapted to contact theouter surface of retaining sleeve 122 so that camming sleeve 128 isretained against retaining sleeve 122 in a rotatably slidable relation.Other surfaces and surface portions are also contemplated, such as, forexample, an interface surface portion 135, as shown in FIGS. 3 and 5,for coupling camming sleeve 128 to retaining sleeve 122. In addition,contact surface portion 134 may contain one or more detents, or grooves136, as shown in FIGS. 4 and 5, which may extend at least partway aroundthe circumference of contact surface portion 134. Grooves 136 mayfurther extend longitudinally in a direction generally aligned with axisL.

Referring generally to FIGS. 3 and 4, when chuck 102 of the workingportion 12 is assembled, a spring 138 may extend through hole 108 inshaft 104 to bias bearing balls 140 radially outward through holes 126of retaining sleeve 122 and into milled grooves 136 (see FIG. 4). Whenballs 140 enter grooves 136, an audible “click” sounds to inform theuser of a locked or unlocked position. The “click” may also provide theuser with a tactile verification of the position as locked or unlocked.In addition, one or more external surface marks 129 may be included tovisually indicate a locked or unlocked positioned, as shown in FIG. 3.For example, corresponding surface marks 129 may be included on cammingsleeve 128 and retaining sleeve 122.

Spring 138, balls 140, and grooves 136 cooperate to maintain cammingsleeve 128 in a locked position or in an unlocked position. In addition,spring 138, balls 140, and grooves 136 may function to keep cammingsleeve 128 rotatingly retained over retaining sleeve 122. For example, acontinuous circumferential lateral groove (not shown) snapped over balls140 may keep camming sleeve 128 rotatingly retained over retainingsleeve 122. Balls 140 may further assist in supporting camming sleeve128 as it is rotated. Spring 138 may further function to help retainshaft 104 inside retaining sleeve 122.

Rubber o-rings 142 and 144 may be used to assist in creating afluid-tight seal between the components, and which may be retained byfeatures such as groove 125, as shown in FIG. 3, and discussed above.

Referring now to FIGS. 2 and 3, a securing member, such as key pin 146,may include an enlarged contact head 148 and a radially inward-extendingprotrusion, key portion 150. Key portion 150 may be shaped and sized toreside within a complimentary-shaped aperture in securing shaft 104, aswill be described. Contact head 148 resides generally within slot 127 ofretaining sleeve 122. Key portion 150 extends radially inward throughkey-hole 120 of milled-away portion 114 of shaft 104 and into bore 110.Springs 118, residing within spring retaining slots 116, contact seatingsurfaces 152 (see FIG. 2) on the underside of contact head 148 to biassecuring member 146 radially outward. When chuck 102 of the workingportion 12 is assembled, camming surface portion 132 contacts the outerradial side of contact head 148.

Referring now to FIGS. 6A and 6B, top views of two exemplaryflat-shanked cutting blades for use with chuck 102 are shown. Beginningwith FIG. 6A, blade 200 has a cutting portion 202 with a serrated edge204. It will be understood that other cutting shapes and structures maybe used for cutting portion 202.

Blade 200 has a flattened shank 206 having an aperture 208 cuttherethrough. Aperture 208 is substantially sized to be complimentary tokey portion 150 of securing member 146. Aperture 208 has two ends 208 aand 208 b that, in the example shown, are each substantially circular inshape and, here, are identical in shape. According to one embodiment,each end 208 a and 208 b may have a center point 209 and 211 andcircumferences 217 and 219. Radiuses 213 and 215 extend from centerpoints 209 and 211, respectively. Ends 208 a and 208 b are spaced apartfrom one another by an offset distance 221. Thus, the distance betweencenter points 209 and 211, is greater than the sum of radiuses 213 and215 (see FIG. 6A).

As shown in FIG. 6B, a pair of inwardly directed ridges 223 may beprovided between circumferences 217 and 219, and which exclude portionsof non-complimentary key portions. In one exemplary embodiment, theshank aperture and key portion have complimentary profiles whichresemble an hourglass. In some embodiments, the shank aperture and keyportion have a shape that is square, rectangular, dumbbell shaped,circular, scalloped, among others. In other embodiments, the profilesare non-symmetrical and may include a lateral bias such that the blademay be securable in only one orientation. For example, the aperture andkey portion may be located lateral from axis L such that the aperture isan open notch in a side of the shank, rather than an enclosed aperture.In yet other embodiments, more than one aperture and more than one keyportion permit secure and consistent blade alignment.

The shape of aperture 208 ensures that only a key having a substantiallycomplimentary shape can be disposed within the aperture. Thus, thechance of blade 200 being used with an incompatible device having anon-complimentary key portion is reduced.

Referring now to FIGS. 7A and 7B, cross-sectional views of blade 200 aredepicted installed in chuck 102. Beginning with FIG. 7A, blade 200 issecured within the chuck 102 by inserting shank 206 inside bore 110 sothat flat shank 206 is retained within slots 112. Flat shank 206 has awidth dimension greater than the diameter of central bore 110, andtherefore extends into, and is received within, slots 112.

Prior to insertion, camming sleeve 128 should be rotated in a directionindicated by rotation arrows R substantially to the position shown inFIG. 7A. In this first position, radially enlarged portion 132 b ofcamming surface portion 132 is adjacent contact head 148 of securingmember 146, thereby permitting springs 118 to bias securing member 146radially outward.

Turning now to FIG. 7B, camming sleeve 128 is then rotated so thatradially reduced portion 132 a is located adjacent contact head 148. Inthis second position, securing member 146 is urged radially inward,which compresses springs 118 and translates key portion 150 into bladeaperture 208, thereby securing blade 200 within chuck 102.

In one embodiment, chuck 102 is configured such that cam sleeve 128 maybe rotated through 180 degrees to completely translate the key portionbetween the first position and the second position. In otherembodiments, chuck 102 is configured such that cam sleeve 128 may berotated more or less than 180 degrees to translate the key portionbetween the first second positions. In one embodiment, chuck 102 isconfigured for 90 degree rotation.

In one embodiment, cam sleeve 128 may be configured to be rotatedperpetually in either the clockwise or counter-clockwise directions.Such perpetual rotatability may increase the ease of use for anoperator. In other embodiments, one or more stops may be included sothat rotation between the first and second positions is limited torotation between the one or more stops.

In order to remove or replace a blade, or other tool within chuck 102,the operations described here are essentially reversed. Camming sleeve128 is rotated so that radially enlarged portion 132 b of cammingsurface portion 132 is positioned adjacent contact head 148, therebypermitting the securing member 146 to be urged radially outward bysprings 118 so that key portion 150 is removed from aperture 208. Blade200 can then be withdrawn from slots 112 and chuck 102.

As noted above, the securing, or locking of blade 200 is accomplishedwithout compressing or reducing a compressible collet against the blade.Thus, according to one embodiment, chuck 102 is a key-less chuck since asurgical tool may be securely attached to chuck 102 without wrenches,chuck keys, and the like. Neither is it required to tighten and loosenthreads by hand, which threads may bind leading to delay in toolchange-over.

In addition, slots 112 have upper and lower opposing inner surfaces 112a and 112 b, as shown in FIG. 2. Opposing inner surfaces 112 a and 112 bare spaced apart by a slot width W that is substantially equal at allpoints between surfaces 112 a and 112 b. Thus, slot width W issubstantially maintained at the same width whether the tool is securedor unsecured in the chuck.

Referring now to FIG. 8, an exemplary cutting blade 300 having a roundedshank is depicted. Blade 300 has a cutting portion 302 with serratededge 304 that may be similar in configuration to cutting portion 202 andedge 204 described earlier. Blade 300 has a rounded shank 306 which mayhave a pair of upper and lower cutaway portions 308 a and 308 b,respectively, at the proximal end of shank 306. Upper and lower cutawayportions 308 a and 308 b define a flattened section 310. An aperture312, which may be shaped and sized similar to aperture 208 describedearlier, is disposed in flattened section 310.

Thus, rounded shank 306 may have a first diameter, or first height,sized to substantially fill cylindrical bore 110, and a second diameter,or second height less than the first height. The second heightcorresponds to the reduced thickness of flattened section 310 afterportions 308 a and 308 b are cutaway. In other embodiments, only oneside of rounded shank 306 is cutaway. This reduction in height providesa unique advantage, such that key protrusion 150 does not have to travelas far to enter and exit the shank aperture. Thus, the travel distanceof key protrusion 150 between the first and second positions is reduced,allowing for a reduction in the maximum thickness of camming sleeve 128.Hence, the overall profile of chuck 102 may be reduced to provide betteraccess, safety, and other benefits.

An additional benefit yielding from the reduced overall profile relatesto the mass of the chuck. The rapid, repetitive direction changeinherent to reciprocating motion is encumbered as more and more mass isadded and made to quickly change direction. Thus, by reducing the massprofile of the chuck, the motor, transmission, and dampening featuresmay all benefit from decreased wear, vibration, and power loss. Inaddition, the size and weight of the handpiece may be further reduceddue to the reduced loading. A reduction in weight and vibration, alongwith improved balance may increase user accuracy and reduce user fatigueduring surgical procedures.

In other embodiments rounded shank 306 has no cutaways but extends itsentire length at the first diameter.

Bore 110 and slots 112 of shaft 104 provide a receptacle that is capableof receiving surgical tools having a substantially rounded shankcross-section, such as blade 300, or a substantially flattened flatcross-section, such as blade 200. Rounded shank 306 is sized and shapedto be retained within bore 110 of shaft 104. Thus, rounded shank blade300 is inserted into bore 110 in substantially the same manner as blade200, however, no portion of shank 306 will be disposed within slots 112of shaft 104. Blade 300 is similarly secured within chuck 102 byrotating camming sleeve 128 to bias securing member 146 radially inwardso that key portion 150 passes through aperture 312 of shank 306. Blade300 is also removed from chuck 102 in the same manner as blade 200.

Referring now to FIG. 9A, an exemplary rasp tool having a rounded shankis depicted. Rasp tool 400 has a working portion 402 with rasp surface404 Rasp tool 400 has a rounded shank 406 which may have a pair of upperand lower cutaway portions 408 a and 408 b, respectively, at a proximalend of shank 406. Upper and lower cutaway portions 408 a and 408 bdefine a flattened section 410. An aperture 412, which is shaped andsized similar to aperture 208 described earlier, is disposed inflattened section 410.

According to one exemplary embodiment shown in FIG. 9B, a rasp tool 420,usable in place of rasp tool 400, may include a rounded shank withpre-configured bends or contours, such as offset bends 414 a and 414 b.Thus, a proximal shank portion 416 is generally aligned with a firstlongitudinal axis L₁, and a distal shank portion 418 is generallyaligned with second longitudinal axis L₂. Axis L₁ is generally offsetfrom axis L₂ by an offset distance D. An offset shank may be configuredto promote access and visibility, though other shank configurations arecontemplated, such as a shank with a single 90 degree bend transverse toaxis L₁, for example.

In some applications, it may preferable to have a round-shanked surgicaltool because the column strength is greater at extended distances. Forexample, a long-reach flat-shanked blade may be more prone to bucklingthan a similarly extended round-shanked blade. Other applications, notrequiring an extended reach, may require the thin kerf and cuttingefficiency of a flat-shanked blade. Thus, the novel chuck disclosedoffers an advantage to users who may now easily change between round-and flat-shanked tools without wrenches, special chuck keys, and thelike.

In addition, procedures involving increased pressures, or alternatingtool force directions—such as may prevail in a rasping application—maybenefit from a round shank. A rasping tool may include a head that hasmore mass than a saw blade, such that increased pull-out forces act onthe shank during the reciprocating instrument's upstroke. In such asituation, the present disclosure may offer an advantage over a frictionlocking collet, such as a split jaw collet, by providing a physicalinterference locking protrusion extending through the shank aperturethat may resist such forces. In addition, locking protrusion 150 mayprevent axial rotation of a rounded shank, especially axial rotation ofan offset rounded shank, as shown in FIG. 9B. Working pressure appliedto working portion 402 may be magnified by offset distance D to create arotational moment introducing torque T about axis L₁. Undesired axialrotation during a surgical procedure could be detrimental. However,according to this embodiment, locking protrusion 150 structurallyimpedes rotational motion due to the torque T to keep rasp tool 400 fromspinning within the collet. Although the offset shank is shown on a rasptool, it is understood that the offset shank may be used with any tool,including for example, saw blades, chisels, burs, and others.

In one embodiment a rounded shank may include one or more lateralextensions which are longitudinally aligned but project radiallyoutwardly from the outer surface of the shank. The lateral extensionsmay extend into existing slots 112 or into additional slots or key-ways,and may resemble, at least partially, the edges of a flat shank. Inother embodiments, the lateral extensions may be bosses, or they may beformed from key-stock, for example.

It is further noted that in the embodiment shown, the chuck is akey-less chuck. Accordingly, the chuck is configured to lock and unlockthe tool without requiring a chuck key or other tool component to aidwith controlling the chuck. Instead, the chuck may be turned by hand,and may include flats or slight recesses that aid in gripping the chuckwith a user's fingers. Either a flat- or round-shank tool may haveanti-rotation and anti-pullout features for securing the tool in akey-less chuck, the aperture may have a pair of side walls having alength with a width between them and distal and proximal end walls. Theside wall length may be greater than the width between the side walls.Thus, an anti-rotation feature may comprise a flattened shank edge of aflat-shank blade or the sidewalls in an aperture of either type ofshank. An anti-pullout feature may comprise the proximal end wall of anaperture of either type of shank.

It can be seen from the foregoing description that rotation of cammingsleeve 128 about retaining sleeve 122 will move securing member 146between a first position and a second position. In the first position,key portion 150 is not substantially withdrawn from the receptacle ofshaft 104 so that a surgical tool shank may be inserted or removedtherefrom. In the second position, key portion 150 is disposedsubstantially within the receptacle of shaft 104 so that, if a surgicaltool shank is present within the receptacle, key portion 150 will bedisposed through the aperture of the surgical tool shank, therebysecuring the tool within chuck 102.

In operation for reciprocating motion, instrument 10 is actuated bymotor 15 to move the blade, rasp, chisel, or other tool in areciprocating manner represented by motion arrows M, as shown in FIGS.7A-9. Motor 15 rotates pinion gear 68 which, in turn, rotates eccentriccrank 76. As crank 76 is rotated, its movement reciprocates connectingrod 86 and reciprocating shaft 88, as well as chuck 102. It should beunderstood that other embodiments may provide reciprocating motion inother directions, such as circular or transverse directions.

In one exemplary embodiment, a round shank aperture and correspondingkey portion have complimentary profiles which resemble an hourglass. Inother embodiments, the profiles are non-symmetrical and may include alateral, bias or offset such that the blade may be securable in only oneorientation. For example, the aperture and key portion may be locatedlateral from axis L such that the aperture is an open notch in a side ofthe shank, rather than an enclosed aperture. In yet other embodiments,more than one aperture and more than one key portion permit secure andconsistent blade alignment.

These embodiments for varying features of the apertures andcorresponding key portions of either round- or flat-shank tools mayprovide proprietary protection. For example, an aperture configured withone of an hourglass shape, an asymmetrical shape, and a longitudinaloffset may prevent non-proprietary blades from being used with thedisclosed chuck. Alternatively, corresponding variations to key portionfeatures may prevent a non-proprietary chuck from being used with thedisclosed surgical tools.

While the invention has been shown in only one of its forms, it shouldbe apparent to those skilled in the art that it is not so limited, butit is susceptible to various changes without departing from the scope ofthe invention.

1. A chuck for securing a surgical tool having a shank with a securingaperture within a reciprocating motion surgical instrument, comprising:a shaft defining an axis and having a receptacle for receiving the shankof the tool; and a securing member carried by the shaft that isselectively moveable between a first position wherein the member issubstantially withdrawn from the receptacle to permit the insertion andremoval of the surgical tool, and a second position wherein the memberis substantially located within the receptacle and through the securingaperture to secure the surgical tool within the receptacle.
 2. The chuckof claim 1 further comprising a camming sleeve mounted about the shaft,the camming sleeve being rotatable about the axis, the camming sleevehaving an internal cam that moves the securing member from a first to asecond position.
 3. The chuck of claim 2 further comprising at least onspring, the securing member being spring biased toward the firstposition, the spring being configured to displace the securing memberfrom the second position to the first position.
 4. The chuck of claim 3wherein the securing member comprises: a head that provides a seatingsurface to contact a portion of the at least one spring for biasing thesecuring member radially outward to the first position; and a securingkey portion extending therefrom shaped so as to be receivable in akey-shaped opening of the surgical tool to secure the surgical toolwithin the receptacle.
 5. The chuck of claim 4 wherein the securing keyportion is substantially hourglass shaped.
 6. The chuck of claim 2wherein the camming sleeve comprises a camming surface directed radiallyinward which slidingly contacts the securing member, the camming surfacebeing radially graduated to provide a radially enlarged portion and aradially reduced portion so that the securing member is selectivelymovable radially between its first and second positions as the cammingsleeve is rotated about the axis.
 7. The chuck of claim 2 wherein thecam sleeve is rotatable relative to the shaft through a range of 360degrees in both clockwise and counter-clockwise directions.
 8. The chuckof claim 1 wherein the receptacle comprises a cylindrical bore in theshaft to receive a surgical tool having a substantially cylindricalshank.
 9. The chuck of claim 8 wherein the receptacle comprises atransverse slot extending into sidewalls of the shaft to receive asurgical tool having a substantially flattened shank.
 10. A chuck forsecuring a surgical tool to a reciprocating surgical instrument, thechuck comprising: a shaft defining an axis and having a cylindrical boreextending along the axis, the bore shaped to receive a substantiallyrounded tool shank, the shaft also having a pair of transverse slotsextending into the shaft along a plane passing through the axis forreceiving a substantially flattened tool shank, the transverse slotsintersecting with the cylindrical bore; and a securing member carried bythe shaft and being radially movable relative to the bore both inwardlyand outwardly to secure a surgical tool in the chuck.
 11. The chuck ofclaim 10 further comprising a cam sleeve rotatingly retained around theshaft and the axis, the cam sleeve having first and second internalsurface portions, the first surface portion having a cammed surfaceengaging the securing member to move the securing member from theoutward to the inward position, the second surface portion having acircumference equally spaced from the axis.
 12. The chuck of claim 11further comprising a retainer sleeve arranged between the cam sleeve andthe shaft, the second surface portion of the cam sleeve rotatinglyengaging the retainer sleeve, the retainer sleeve having a slot which issized to permit movement of the securing member between the inward andoutward positions.
 13. The chuck of claim 12 wherein the retainer sleeveand the shaft include aligned transverse holes, the chuck furthercomprising: opposing balls slidingly arranged in the aligned transverseholes, the cam sleeve second surface portion including grooves alignedwith the axis and configured to receive the balls when the cam sleevegrooves are aligned with the balls such that the cam sleeve is securedagainst free rotation by the balls; and a spring biasing the ballsradially outwardly.
 14. The chuck of claim 11 further comprising: adetent formed within the cam sleeve second surface portion for receivinga ball member; and a ball member retained within the shaft and biasedradially outward to become disposed within the detent upon rotation ofthe cam sleeve to a predetermined position.
 15. The chuck of claim 14wherein the ball becoming disposed in the detent creates at least one oftactile feedback and audible feedback to an operator.
 16. The chuck ofclaim 10 further comprising a spring coupled to the shaft to bias thesecuring member outwards.
 17. The chuck of claim 10 wherein thetransverse slots have upper and lower, opposing inner surfaces, andwherein the opposing inner surfaces are spaced apart by a slot widththat is substantially the same across the transverse slots whether thetool is secured or unsecured in the chuck.
 18. A system for treating atissue structure during a surgical procedure, comprising: areciprocating surgical instrument, comprising: a motor having arotatable spindle; a transmission mounted to the spindle for convertingrotating movement of the spindle to reciprocating movement; a surgicaltool chuck coupled to the transmission, the chuck comprising: areceiving shaft defining a longitudinal axis and having a toolreceptacle and a radially extending proximal opening; a locking memberslidingly coupled to the receiving shaft, the locking member having aprotrusion extending therefrom; and a camming sleeve rotatingly retainedon the shaft, the camming sleeve having an internally cammed surface;and a surgical tool having a distal end and a proximal end, the proximalend configured to be received into the tool receptacle, the surgicaltool having an aperture disposed to correspond with the radiallyextending proximal opening of the receiving shaft when the surgical toolis disposed in the attachment receptacle, wherein the locking member isselectively moveable between a first position and a second position, thefirst position wherein the protrusion is withdrawn from the proximalopening of the receiving shaft to allow insertion and removal of thesurgical tool, the second position wherein the protrusion issubstantially received within the proximal opening of the receivingshaft and the aperture in the surgical tool to secure the surgical toolwithin the chuck, the cammed surface configured to urge the protrusioninto the second position.
 19. The system of claim 18, further comprisinga spring coupled to the shaft and disposed to bias the protrusion towardthe first position.
 20. The system of claim 19 wherein the lockingmember has a head portion with an inner surface, the protrusionextending therefrom, the head portion having a length dimension widerthan the protrusion, the inner surface having at least one springengagement feature for engaging the spring.
 21. The system of claim 18wherein the tool receptacle comprises a cylindrical bore in the shaft toreceive a surgical tool with a substantially cylindrical shank.
 22. Thesystem of claim 21 wherein the surgical tool has a shank with first andsecond diameters, the first diameter sized to substantially fill thecylindrical bore and the second diameter representing a reducedthickness configured to reduce a travel distance of the protrusionbetween the first and second positions, thereby reducing an overallprofile of the chuck.
 23. The system of claim 21 wherein the toolreceptacle further comprises a transverse slot extending throughopposing sidewalls of the shaft to receive a surgical tool with asubstantially flattened shank.
 24. The system of claim 18 wherein thecamming surface is directed radially inward and slidingly contacts thelocking member, the camming surface being radially graduated to providea radially enlarged portion and a radially reduced portion so that thelocking member is selectively moveable radially between its first andsecond positions as the camming sleeve is rotated about the longitudinalaxis.
 25. The system of claim 18 wherein rotating the cam sleeve through180 degrees completely translates the protrusion between the firstposition and the second position.
 26. The system of claim 21 wherein thesurgical tool has an offset shank including a first portion generallyaligned with the longitudinal axis and a second portion generallyaligned with an offset axis, the offset axis being generally parallel tothe longitudinal axis and offset from the longitudinal axis by an offsetdistance.
 27. The system of claim 18 wherein the surgical tool chuck iskey-less.
 28. The system of claim 18 wherein the surgical tool has ashank, the shank having an anti-rotation feature and an anti-pulloutfeature for securing the tool in a key-less chuck, the aperture having apair of side walls having a length, a width between the pair of sidewalls, and a proximal end wall, the side wall length being greater thanthe width between the pair of side walls, wherein the anti-rotationfeature is at least one of a flattened shank edge and the pair ofsidewalls and wherein the anti-pullout feature is the proximal end wall.29. The system of claim 18 wherein the surgical tool aperture is one ofan hourglass shape, an asymmetrical shape, and a longitudinal offset.